A ring of devices, such as port ASICs or stacked network devices, can be configured to operate together to aggregate functionality. For example, routers can be stacked so that they appear to a user as a single device having the aggregate functionality of the stacked individual devices.
A supervisory functionality must be defined to manage the individual devices to transfer packets between ports on different devices and to perform other functions. The supervisory functionality can detect whether one of the links between devices or ports is not functional but the identity of the non-functional link must be determined by inspection.
For example, if the devices are port ASICs mounted on a PCB, then a physical hardware probe is used to determine the identity of the link that is not functioning properly. The use of a hardware probe is time consuming and expensive since it requires disassembly of the box and a skilled technician to perform the test.
Accordingly, new techniques for identifying faulty links in a ring of devices are important to increase efficiency.